Nomenclature. 133 minutes. 130 marks. Page 1 of 19

Transcription

1 3..5. Nomenclature 33 minutes 30 marks Page of 9

2 M. (a) (i) C=C + ½O ( ) Product () M Correct balanced equation () M C 4 C =C C C NOT [O] For M, allow credit when C 4 O C C O are used strained (ring) () NOT weak bonds NOT unstable Credit "stressed" (iii) Structure: () Use: antifreeze () or production of Terylene or feedstock for polyester or PET NOT plasticiser NOT solvent NOT de-icer NOT alcohol 5 (b) Credit mark for a correct formula for but--ene Credit mark for any pair of cis / trans isomers Geometric(al) Or cis-trans Or diastereoisomerism NOT stereoisomerism 3 [8] Page of 9

3 M. (a) (i) Molecule/compound/consists/composed/made up of hydrogen and carbon only () C n n+ () (iii) C 6 4 only () Do not credit structures alone or in addition. 3 (b) Chemically similar / react in same way / same chemistry Differ by C gradation in physical properties specified trend e.g. b.p. same functional group Any, marks + Not same molecular formula (c) (i) Same molecular formula () NOT same Mr different structural formula / structures () (or atoms arranged in different way) NOT different spatial arrangements Only credit M if M correct -methylpentane (),-dimethylbutane () (iii) correct condensed / structural formula Penalise sticks once Penalise absence of vertical bonds once penalise badly drawn bonds once (vertical between atoms) 6 (d) (i) M % by mass of = 7.7(0)% () M mol = 7.70 / = 7.70 mol C = 9.3 / = 7.69 () M3 (ratio : ) C Credit variations for M e.g. 78 = 6 and = 6 Correct answer = 3 marks Page 3 of 9

4 (C has empirical mass of 3 and = 6 ) C 6 6 () Correct answer mark 4 [5] M3. (i) Isomer C 3 C C C O Name butan--ol -methylpropan--ol (-)methyl propan--ol () NOT prop--ol butan--ol () -butanol NOT but--ol NOT hydroxy No RE Allow e in the names Structural () chain and position(al) 3 [3] M4. (a) (i) compounds/mixtures/alkanes/hydrocarbons/molecules with a boiling point range/similar boiling point/similar number of carbon atoms/similar chain length; (insist on similar rather than same ) (ignore references to size or M r ) (penalise references to bond breaking/cracking as contradictions) molecules have different boiling points/intermolecular forces/sizes/chain lengths/m r ; (ignore references to melting points) (credit the idea that molecules condense at different temperatures) Page 4 of 9

5 (iii) the column has a higher temperature at the base (Q of L mark) the column has a lower temperature at the top; (the statement needs to be expressed in good English and show a clear understanding of the correct temperature difference) (penalise negative positive temperature gradient without qualification to what the candidate means, otherwise ignore) (ignore references to the boiling points of the molecules) (credit correct statements which use specific temperatures with a maximum temperature of 500 C at the base) (b) (i) C ½O 8CO + 9 O; (or double this equation) correctly drawn structure of,,3-trimethylpentane (penalise the use of sticks once on the paper, including the structures in the (a) and (c)(iii )mechanisms) (credit correctly condensed structures) (c) cracking produces/makes ethene/propene/alkenes/motor fuels/petrol cracking makes more useful products/high(er) value products cracking satisfies the high demand for small(er) products; (ignore the idea that cracking makes or leads to plastics or polyethene) (high demand needs to be qualified) (d) (i) carbocation carbonium ion; (do not credit examples or formulae, but otherwise ignore) (credit carbon cation ) zeolite aluminosilicate Al O 3 ; Page 5 of 9

6 (e) (i) M: (free) radical; (credit alkyl radical) (do not credit examples or formulae, but otherwise ignore) (penalise radical substitution hydrocarbon radical as contradictions) M: homolysis homolytic fission/splitting/cleavage C-C / C- bonds break; alkene(s); (credit small or short chain alkenes ) (penalise cycloalkenes ) (penalise additional types of compounds (e.g. branched alkanes) as a contradiction) (do not credit examples or formulae, but ignore if these are correct and in addition to the word alkene ) [] M5. (a) (i) any two from: show a gradation/trend/gradual change in physical properties/ a specified property differ by C chemically similar or react in the same way have the same functional group (penalise same molecular formula ) (penalise same empirical formula ) (iii) fractional distillation or fractionation contains only single bonds or has no double bonds (credit every carbon is bonded to four other atoms provided it does not contradict by suggesting that this will always be ) Page 6 of 9

7 (b) (i) the molecular formula gives the actual number of atoms of each element/type in a molecule/hydrocarbon/compound/formula (penalise amount of atoms ) (penalise ratio of atoms ) C 4 30 only (penalise as a contradiction if correct answer is accompanied by other structural formulae) (iii) C 0 + 5½O 0C + O (or double this equation) (c) (i) ½N + ½O NO (or double this equation) Platinum or palladium or rhodium (iii) CO + NO CO + N or NO N + O or (ignore extra O molecules provided the equation balances) C + NO CO + N (or half of each of these equations) C NO 8CO + ½N + 9 O (or double this equation) [0] M6. (a) General formula; Chemically similar; Same functional group; Trend in physical properties eg inc bp as M r increases; Contains an additional C group; Any two points. max Page 7 of 9

8 (b) (i) C 3 6 Cl; All bonds and atoms must be shown. Allow any order of elements. Do not allow EF consequential on their wrong displayed formula. Same Molecular formula/ both C 6 C l / same number and type of atoms; Different structural formula/ different structure/ different displayed formula; Not atoms or elements with same MF CE=O. Allow different C skeleton. If same chemical formula can allow M only. M insufficient to say atoms arranged differently. M consequential on M. (c) M r =8 for total reactants; = 67.98%; Allow or 68.0 or 68%. (d) (i) Bp increases with increasing (molecular) size/ increasing M r / increasing no of electrons/increasing chain length; Atoms CE =0. Increased VDW forces (between molecules) (when larger molecule)/ bigger IMFs; QWC Not dipole-dipole or hydrogen bonds. If VDW between atoms in M CE = 0. Fractional distillation/ fractionation/ GLC/chromatography; [] Page 8 of 9

9 M7. (a) (i) single (C-C) bonds only/no double (C=C) bonds Allow all carbon atoms bonded to four other atoms Single C- bonds only = 0 C= CE C and (atoms) only/purely/solely/entirely Not consists or comprises Not completely filled with hydrogen C molecules = CE Element containing C and = CE C n n+ Formula only C x x+ (b) (i) C 5 + 8O 5CO + 6 O Accept multiples Ignore state symbols gases produced are greenhouse gases/contribute to Global warming/effect of global warming/climate change Allow CO or water is greenhouse gas/causes global warming Acid rain/ozone CE = 0 (c) carbon Allow C Allow soot (d) (i) C 9 0 C 5 + C 4 8 C 9 0 C 5 + C 4 Accept multiples Plastics, polymers Accept any polyalkene/haloalkanes/alcohols (iii) so the bonds break because the bonds are strong IMF mentioned = 0 Page 9 of 9

10 (e) (i),4-dibromo--chloropentane/-chloro-,4-dibromopentane Ignore punctuation Chain/position/positional Not structural or branched alone [] M8. (a) (Different) boiling points Ignore mp s, references to imf, different volatilities (b) (i) Compound which have the same molecular formula Accept same no and type of atom for M But If same (chemical) formula M = 0 but allow M If empirical formula CE = 0/ but different structures/different structural formulae/different displayed formulae M dependent on M 3-methylbut--ene only ignore commas and hyphens Page 0 of 9

11 (iii) Allow any correct structure with a cyclic alkane Do not allow (c) C 3 8 only i.e with an missing on one C Making plastics/used to make polymers or polythene/used to make antifreeze/make ethanol/ripening fruit/any named additional polymer not used as a plastic/polymer/antifreeze not just polymers we need to see that they are being made [6] Page of 9

12 M9. (a) (Same) General formula/allow a named homologous series with its general formula Chemically similar/same (chemical) reactions Same functional group Trend in physical properties/eg inc bp as M r increases (b) (c) (Molecules) increase by C /M r = 4 Any two points Fractional distillation/fractionation/chromatography Allow GLC (Molecules/compounds/substances) with the same molecular formula/same number and type of atoms Allow alkanes with same molecular formula Allow same chemical formula in M = 0 but can allow M but different structural formula/different displayed formula/different arrangement of atoms/different structures Not different positions in space,4-dimethylhexane M dependent on M (d) C 4 9 Ignore the absence of dash and/or commas less surface contact/less surface area/less polarisable molecule so fewer/weaker/less Van der Waals /vdw forces Allow more spherical or fewer points of contact Not smaller molecule/not more compact molecule/not shorter chain Allow converse arguments Must be comparative answer ie not just few VDW forces QoL Assume it refers to the branched isomer [9] Page of 9

13 Allow other balanced equations which give C and CO/CO M0. (a) C n n+ Allow x in place of n (b) Chain Must show every bond Allow branched chain (c) C 9 0 Only To break the (C-C and/or C-) bonds M=0 if break C=C To make products which are in greater demand / higher value / make alkenes Not more useful products Allow specific answers relating to question (d) C 5 + 3O 5C + 6 O Causes global dimming / exacerbates asthma / causes breathing problems / makes visibility poor / smog Apply list principle Ignore causes cancer / toxic Page 3 of 9

14 (e) (x 00) 74.48% 3 Allow 74.5% Only (f),3-dichloro-3-methylpentane Ignore punctuation C 3 6 Cl Only [3] M. (a) (i) C n n / C x x Fractional distillation / GLC / gas liquid chromatography / fractionation Do not allow cracking / distillation (b) (i) But--ene / butene Ignore hyphens and commas Do not allow butene- / but--ene / butane / butane /alkene / C 4 8 / propene / straight-chain alkene A structure of cyclobutane or methyl-cyclopropane Allow skeletal formula. (c) (i) C 5 3 C C 7 6 Do not accept multiples. Thermal cracking Not catalytic cracking or cracking. Page 4 of 9

15 (iii) To produce products that are in greater demand / more valuable / more expensive / more profitable The (unsaturated) alkene or the (unsaturated) molecule or X produced can be polymerised or can be made into plastics. Ignore more useful products. Break (C C or C ) bonds Allow to overcome the activation energy. Allow to break the carbon chain. Penalise breaking wrong bonds. (d) (i) Only. (iii) Fuel / LPG Allow camping gas, lighter fuel, propellant, refrigerant, cordless appliances. Do not allow petrol or motor fuel. Ignore natural gas. C O 4C + 5 O Accept multiples. (iv) SO / sulfur dioxide If other sulfur oxides, mark on. (v) Calcium oxide / CaO / lime / quicklime Allow CaCO 3 / allow Ca(O) or names. Allow any solid base. M dependent on M. Do not allow limewater. Neutralisation Allow acid-base reaction. Allow flue gas desulfurisation / FGD (e) (Molecules) are similar sizes / have similar M r / have similar number of electrons Chemical error CE = 0/ if breaking bonds. Allow similar number of carbon and hydrogen atoms / similar surface area / similar chain length. Can accept same number of carbon atoms. Do not accept same number of atoms / same number of bonds. Ignore similar amount of bonds. Page 5 of 9

16 Similar van der Waals forces between molecules / similar intermolecular forces (IMF) Not similar incorrect IMF eg dipole-dipole [6] M. (a) -bromo-,3-dimethylbutane Ignore punctuation. C n n+ Br or C n n+ X or C x x+ Br Any order. Stronger / more vdw (forces) between molecules (of -bromohexane) QoL Allow converse arguments for Z Not just more IMF. Ignore size of molecule. (b) C 4 Cl Any order [5] M3. (a) (i) (Compounds with the) same molecular formula Allow same number and type of atom for M Ignore same general formula. Page 6 of 9

17 But different structural formula / different displayed formula / different structures / different skeletal formula M dependent on M Not different positions of atoms / bonds in space. But--ene Allow but--ene. Allow but ene. Ignore punctuation. (iii) ()-methylprop-()-ene Do not allow -methyleprop--ene. (iv) Do not allow skeletal formulae. Penalise missing and missing C (b) (i) C O 4C + 4 O Accept multiples. Exacerbates asthma / breathing problems / damages lungs / smog / smoke / global dimming Ignore toxic / pollutant / soot / carcinogen. Do not allow greenhouse effect / global warming / acid rain / ozone. (c) (i) C 6 34 Allow 34 C 6 C and must be upper case. Page 7 of 9

18 Jet fuel / diesel / (motor) fuel / lubricant / petrochemicals / kerosene / paraffin / central heating fuel / fuel oil Ignore oil alone. Not petrol / bitumen / wax / LPG / camping fuel. (d) (i) C NO 8CO +.5 N + 9 O Accept multiples. Ir / iridium Pt / platinum Pd / palladium Rh / rhodium [] Page 8 of 9

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